package chapter_2;

import java.util.Scanner;

public class Test21 {
    public static void main(String[] args) {
        System.out.println(f(1));
        System.out.println(f(9));
    }
    public static int f(int n){
        if(n == 10){
            return 1;
        }else {
            return  (f(n+1)+1)*2;
        }
    }
}
